The truth about those expiration dates on your groceries

Deciding whether or not that untouched yogurt carton or pack of hot dogs in your fridge has gone bad is simply a matter of reading the expiration date on the label, right?

Hardly.

For starters, is there a date? And if so, which date should you go by? “Expires on”? “Sell by"? "Best before”?

Most of the time, dates have nothing to do with whether a food is safe to eat or spoiled.

It’s confusing. Date labeling of food products isn’t required under federal law, so the practice varies widely between states and food companies. And here’s the real kicker: Most of the time, the dates have nothing to do with whether a food is safe to eat or spoiled.

The problem is that none of these terms connote any sort of universally established meaning, nor do they have any legal definition, says Dana Gunders, senior scientist at the National Resources Defense Council (NRDC), which put the issue in the spotlight in its 2013 report “The Dating Game,” published with the Harvard Food Law and Policy Clinic.

Most of the time, the dates have nothing to do with whether a food is safe to eat or spoiled.

It all adds up to inconsistent labeling, consumer confusion, and a lot of wasted food—about $165 billion dollars worth a year, or 40 percent of our food supply, by NRDC estimates.

But a federal bill expected to be introduced later this month is poised to change that. The proposed legislation outlines a standardized labeling system that would finally make clear two things: a food's quality date and its safety date.

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The currently meaningless phrase “Best if used by” would indicate when a product will no longer taste its best. The date past which the product would no longer be safe to eat would be noted as “Expires on.” (Legislation proposed just a few weeks ago in California calls for similar standards.)

But although mandatory (and universal) date labeling is on the horizon, for the time being we still have to navigate the current confusing language.

Commonly used date labels:

"Packed on": This is when a product was put in its package. You can ignore this date.

"Sell by": This date is a manufacturer’s way of telling a grocery store how long it should keep the product on its shelves. It’s a business-to-business communication that has nothing to do with whether a food is safe to eat, Gunders says. In other words, don’t worry about it.

"Best by," "Use by," "Best if used by," "Best before": These all generally mean the same thing: the date when a manufacturer says a food is no longer at its peak quality and flavor. The texture or color may change. It might not taste as good. However, it doesn’t mean it’s not safe to eat after that, Gunder says.

So those "expired" yogurts might be perfectly fine.

"Freeze by," "Use or freeze by": This is the manufacturer’s suggestion for when you should freeze something—again, with optimal quality in mind—if you’re not using it right away.

"Expires on": Theoretically, this date refers to when a food is no longer okay to eat, but there's no guarantee. “In practice, it just varies,” Gunders says.